COMMITTED ADIPOGENIC PROGENITORS ARE RESPONSIBLE FOR NOVEL ADIPOCYTE GENERATION IN RESPONSE TO DIETARY STIMULI

Abstract

During adult life white fat depots can expand via hyperplasia and adipocyte infiltration can appear in aging or disease of non-adipose tissues. These observations suggest that stem/progenitor cells exist that can respond to a variety of stimuli to generate new adipocytes. We used a combination of surface markers to prospectively identify a population of cells containing all adipogenic colony-forming potential in skeletal muscle, subcutaneous and perigonadal adipose depots (adipogenic progenitors, APs). We did not observe any generation of cartilage, bone or muscle from AP cultures, suggesting that APs are committed to the adipocyte lineage. Confocal- and immunoelectron- microscopy analysis on tissues from BrdU-treated high fat diet-fed animals confirms the production of new adipocytes during weight gain. APs appear to participate in this response in a depot- specific manner. Furthermore, we observed a significant correlation between the size of the fat pad and frequency of actively cycling AP cells. Taken together, we show that we have identified an abundant population of lineage-restricted adipogenic progenitors. Importantly, our data suggests that during weight gain, new adipose generation relies on proliferation of these cells. AJ is supported by a Vancouver Coastal Health–CIHR–UBC MD/PhD Studentship Award.